Method of purifying aromatic alcohols and derivatives



the steps Patented Sept. 28, 1926.

UNITED STATES MARK n. YUTNAM AND JOSEPH W. BRITTON', TO THE DOW CHEMICAL 0F MIDLAND,

mrcmean, assrdnoas comranx.

. mn'rnon or runrrxme anoma'rrc ALCOHOLS AND nnnrva'nvns.

No Drawing.

present methods of manufacture of benzoic acid from toluene consist of direct oxidation of toluene to benzoic acid, which is very expensive; or the partial or complete chlorination of the methyl group wit subsequent oxidation or hydrolysis. This latter method, which while very economical, is open to the objection that contaminated by ortho and para chlorbenzoic acids' which are found as by-products and which greatly impair the value of the finished product. Up to the present time, so far as we are aware, no commercially successful method for the complete removal of these by-products has been developed. We have, however, discovered that by heating a salt of the benzoic acids in the presence of a suitable catalyzer, under pressure with a volatile or fixed alkali, preferably ammonia, the chlorbe'nzoic acid is converted into an amino or hydroxyl compound which candbe read'ly separated from the benzoic ac1 v The invention, accordingly, consists of hereinafter fully described and particularly pointed out in the claims, the following description setting forth but one of the various ways in which the principle of the invention may be used.

The following is a specific example of the operation of-our improved process as aplied to the purification of benzoic acid, viz, 100 grams of benzoic acid, containing between one and two per cent of chlorbenzoic acids, was converted to the sodium salt an was mixed with aqueous ammonia an cuprous chloride as a catalyst and heated in a closed reactor at'a temperature of 200 C. for four hours. The reaction mixture was then removed 'from the reactor, the excess ammonia recovered by distillation, and the benzoic acid liberated with sulphuric acid. After cooling, the benzoic aci was filtered, washed and recrystallized from water. The benzoic acid thus obtained showed less than one one-hundredth (0.01) per cent of chlorine. V

Ben zyl alcohol is also manufactured from chlorinated toluene by the general process hereinbefore referred to and is similarly contaminated by traces of ortho and para- I These may be remove in the same manner as just described in the case of benzoic acid. It will also be understood that any ofthe aromatic alcochlor derivatives.

Application filed October 1, 1925. Serial No. 59,959.

h be purified of such halogen compounds the treatment the product is with an aqueous hols and acids when produced by the hydrolysis of aromatic halogen compoundsare more or less contaminated by ring halogen compounds.

Y herein prescribed, viz, ing the corresponding salt (where the comound is not already in this form, it of course requires first to be converted as in the specific example given above), in the resence of a suitable catalyzer with a vola- Any such alcohol or acid may by heattile or fixed alkali, preferably ammonia, and

then separating out the resulting amino or hydroxyl compound into whichthe impurity is converted.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the method herein disclosed, provided the step or steps stated by any of the fol-- lowing claims or the equivalent of such stated step or steps be employed.

' We therefore particularly point out and distinctly claim as our invention v 1. In a method of removing a halogenated impurity from an aromatic alcohol, orthe corresponding acid or salt, the, step whic consist-s in heating with an aqueous alkaline solution at temeratures from 100 to 400 C.

2. In a method of removing a halogenated impurity from an aromatic a corresponding acid or salt, the step whic consists in heating the impure compound (1 with an aqueous alkaline'solution 1n the d presenceof a catalyst at temperatures from 100 to 400 C.

3. In a method of removing a halogenated impurity'from an aromatic alcohol, or the corresponding acid or salt, the step which consists in heating the impure compound with an aqueous solution of ammoniaat temperatures from 100 to 400 C.

4. In a method of removing a halogenated impurity from an aromatic alcohol, or the corresponding acid or, s alt, the step which consists in heating the impure compound solution of ammonia in the presence of acuprous compound attemperatures from100 to 400 C.

5. In a method of removing a halogenated impurity .from benzoic acid, consists, in heating the impure acid with an aqueous alkaline solution at temperatures from 100 to 400 C.

the impure compound lcohol, or the I v the step which impurity from benzoie acid, the step which the impure a cuprous compound at temperatures from 100"to 400 C.

7. In a method of rembving a halogenated impurity from benzoic acid, the step which consists in heating the impure acid with aqueous solution of ammonia in the presence of cuprous chloride 100 to 400 C.

Signed by us this-28 day of Sept. 1925.

MARK E. PUTNAM. JOSEPH W. BRITTON. 

